Does anyone know how to remove a blackberry device from the list of MDS Registered Devices?

I'm running BES 4.1 sp6 and have MDS Integration Services set up. Under the list of Registered Devices, I have some blackberry devices which I no longer use, these pins have been removed from the system and are no longer associated with any blackberry users. How do I go about trying to clear these unused devices out of the list?

I also have a case where the pin is listed as a Registered Device, but when I try to do a MDS Activation from the handheld, I get an "Activation Error". Looking at the MDSS logs (in debug mode), I see entries: